The hypothesis of this study is that C1 inhibitor may be an important regulator of the generalized capillary leak that develops on ECMO. Release of chemokines may contribute to lung injury and edema during ECMO. Aims We will study 3 subgroups of patients requiring ECMO : 1)neonates without congenital diaphragmatic hernia (CDH), 2)neonates with CDH and 3)pediatric patients with the following aims: 1. Measure C1 inhibitor levels with documentation of activation of the contact and complement systems prior to, during, and after ECMO. 2. Measure chemokine levels in plasma and bronchoalveolar lavage (BAL) samples, before and during ECMO. 3. Assess infants clinically for degree of capillary leak before, during, and after ECMO. 4. Determine whether C1 inhibitor levels correlate with degree of capillary leak in subjects on ECMO. 5. Determine whether chemokine levels in plasma and BAL samples correlate with degree of pulmonary edema in subjects on ECMO